Grade 2 Read-Aloud

Cycles in Nature: Supplemental Guide 2A | The Reasons for Seasons 41

Presenting the Read-Aloud 15 minutes

The Reasons for Seasons

 Show image 2A-1: Earth rotating on its axis

Right now, Earth is moving! Even though you cannot feel it,

Earth is always moving in space in two ways. We have already

heard about one way the earth moves. It is called rotation.

Rotation is the movement of Earth around its axis. This controls

the cycle of daytime and nighttime. The Earth takes twenty-four

hours to turn, or rotate, once on its axis. The earth rotates in a

counterclockwise direction from daytime to nighttime and back to

daytime again.^1 During rotation, the part of Earth that is facing the

sun changes. When it is daytime where you are, that means that

the part of the earth on which you are standing is facing the sun.

Sunlight hits our planet and moves across it from east to west.

This is why we see the sun rising in the east and setting in the

west.^2 Sunset eventually occurs when certain parts of Earth turn,

or rotate, away from the sun, and nighttime begins. This cycle

continues over and over again.^3

 Show image 2A-2: Diagram of Earth revolving around the sun

The second way the earth moves is called revolution. Earth

revolves, or orbits, around the sun in an almost circular path.

Therefore, since you live on Earth, you are traveling around the

sun, too. It takes Earth about 365 days—or one year—to complete

one revolution, or orbit.

Earth is tilted as it orbits the sun. Tilt, or slant, your head to one

side. The earth remains at this same angle and points in the same

direction throughout its entire orbit. Now let’s fi nd out more about

how Earth’s tilt causes the seasonal cycle.

 Show image 2A-3: Orange cut into halves and Earth cut into hemispheres

Earth is divided into hemispheres, or halves. Just like an

orange can be cut in half through the center from side to side.

Earth can also be divided into two parts. Our planet is divided

1 Counterclockwise means to move
in the opposite direction from the
hands on a clock. [Demonstrate
counterclockwise for students.]

2 [Show students which way is east
and which way is west in your
classroom.]

3 Stand up and turn or rotate
one time moving in a
counterclockwise direction. Your
full rotation models the earth’s
rotation as it completes one full
twenty-four hour cycle.